A sliding environment in a half dry state often exists in a sliding portion in a compressor such as an air conditioner and a sliding portion near a piston of an automobile engine, and specifically includes, in a swash plate-type compressor, a sliding portion between a piston rod and a swash plate that drives the piston rod.
In the related art, a sliding member is known that has a coating film formed on a surface thereof, the coating film being formed of a composition obtained by blending a solid lubricant such as polytetrafluoroethylene, graphite and molybdenum disulfide in a binder resin such as a polyimide resin or a polyamide-imide resin. However, there is a trade-off between a lubricity of the coating film provided by blending the solid lubricant and a mechanical strength and adhesion to a member of the coating film, and when it is attempted to improve the lubricity, the strength and the adhesion will decrease. Therefore, it was difficult to achieve both of the above properties.
Depending on the use, the properties can be achieved by optimizing a blending amount of the solid lubricant to balance between the coating film strength and the lubricity. However, with only a solid lubricant of the related art, the decrease of a friction coefficient is limited. It is possible to decrease both a static friction coefficient and a dynamic friction coefficient by applying a lubricating oil agent such as grease or oil to a sliding surface. However, since the lubricating oil agent will be discharged from sliding surfaces in a short period of time due to the sliding, the lubricity cannot be maintained. Also, since solidification or deterioration occurs with time, there is a problem that a friction coefficient will increase.
A lubricating coating may be, for example, a baking coating in which silicone having a functional group at both ends is blended in a thermosetting resin composition (patent document 1), a lubricating coating including a polyamide-imide resin, a reactive silicone oil having an epoxy group, and triazinethiol (patent document 2), a composition in which lubricant is retained in a cavity part of a porous resin film (patent document 3), and a material containing a curable resin, a solid lubricant and a modified silicone oil (patent document 4).